Telephone system.



H. G.- WEBSTER.

. TELEPHONE SYSTEM.

APPLIGATIOIf FILED 3110.13.1902.

PATENTED 001. 22, 1907. Q

. UNITED STATES PATENT ossios.

HARRY G. WEBSTER, OF CHICAGO, ILLINOIS, ASSIGNOR TO KELLOGG SWITCHBOARDAND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A .OORPORATIQNOF ILLINOIS.

TELEPHONE SYSTEM.

I Specification of Letters Patent.

Patented Oct. 22, 1907.

Application filed December BL 1902- Serial No. 135,028-

To all whom it may concern:

Be it known that I, HARRY G. Wnssrnn, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in Telephone Systems, ofwhich the following is a specification.

My invention relates to telephone systems wherein subscribers linesterminate at the central ollice or offices and at which provision ismade for inter-connecting the various lines for conversational purposes.It has special reference to those systems employing. central sources ofcurrent supply, by reason of which the signaling to the central olficeby the subscriber is automatic, whereby current for transmissionpurposes is supplied from the central cities and whereby the supervisoryapparatus is all actuated by current from the said central source.

This invention has for its object the simplification of the circuits,connections and. arrangements by which the above operations areaccomplished, and the provision of a system that is at once rapid,positive and eflicient.

In the accompanying drawing, in which the same reference charactersindicate like parts throughout, the

figure is a diagram of two subscribers lines leading to a central officeand-the apparatus at the central oflice for initiating and completingconnections for conversational purposes. i

In this figure L and L represent subscribers lines extending from theirrespective substations to the central oliice. Upon the line L a singlesub-station A is located, at which is provided an ordinary signalingbell 4, and a condenser 5 preferably permanently connected between thetwo line conductors and a transmitter 6 together with a receiver 7, inabridge (if said line conductors, which bridge ,is normally open at theswitchhook 8. This'apparatus, it will be understood, is in-.

tended merely to typify any desired common battery subscribers set.

At the central office the line is I in thc'line conductor 2 which isgrounded or connected "with the common ofiice return and the other, therelay Rf, connected in the line conductor 3 which is conductively joinedwith the omnibus bar 9 leading from an intermediate pole of the batteryB. These line relays are of high resistancerelatively, say 1000 ohmseach, and control through theirnormally open contacts the local circuitof the line signal S, which is preferably in the form of a smallincandescent lamp.

I have shownupon the line L, we substations C and provided with an answering jack J, and with any number of multiple jacks, I

D, each of which is provided with a transmitter 6, a re ceiver 7 and aswitch-hook 8 in the same relation as described with reference to thesub-stat'on A located on the line L. As before, these partsmay-represent any typeof common battery subscribers sets. The signal ingbells at these stations, however, are not bridged across the line butare shown connected with the different line conductors and with ground.That at the station 0 is connected with the sleeve side of the line I 3,while that at station D is normally joined through the switch-hook withthe tip side of the line 2. At the central-olfice a line signal S isprovided; the local cir-' cult of which is controlled through thenormally open contacts of the two high resistance line relays R and Rlocated respectively in the tip and sleeve conductors of the line, thesleeve conductor of this line being I shown as united through aconductivepath over the omnibus bar 9"- with an intermediate pole of thebattery B". These batteries B and B are preferably grounded at one poland are ordinarily of the storage battery 7 5 type, having a voltage of24 .volts, the bars 9 and 9 being joined with said batteries at a pointto include about 18 volts. These proportions may be varied Withoutdeparting from the principleoi' the invention, but are such as I nowprefer to employ.

The operators apparatus comprises a cord circuit, provided with ananswering plug 1? and with a calling plug P, the tip andsleeve contactsof which are adapt-- ed toengage with corresponding contact surfacesinthe jacks of the lines. The tip contacts of the plugs are joinedtogether through the flexible strands t and t and the interposedcondenser 13, while the sleeve contacts of said plugs are joined by thestrands sand s and the interposed condenser 0 The battery 13 is bridgedacross the answering end oi the cord circuit .and includes upon the tipand sleeve sides thereof the supervisory relays r and 1 each preferablyof about ohms resistance, and which-control the local cir- .cuit of thesupervisory lamp S which is preferably energized from the same battery Band whose said 95 local circuit is normally open at the contacts ofrelay r and normally closed by the contacts of relay 1. The calling 'endof the cord circuit is likewiseconnected with the battery B and isprovided with the supervisory relaysfr and 7*, which similarly controlthe 106 local circuit of the supervisory lamp 8.

The sleeve supervisory relay 2' is provided with an additionalset ofcontacts, the spring 10 serving in its -forward position to complete thetip strand t for.con

versational purposes, but in its normal position to connect the forwardportion of said strand with conductor 11 leading to a high resistanceand high impedance test relay 1, the opposite pole of which is connectedI ,by conductor 12 with the junction point 13 l00ated.

upon conductor 14 which is connected with -tlie lead: I1,

9. The conductor 14 contains a retardation coil 15 vand is thence ledthrough the operators transmitter- 16 to ground. In shunt of thetransmitter 16 is connected the primary winding of the operatorsinduction coil 17 and a condenser 0 The forward contacts of the testrelay r complete a path to ground from a are adapted to be connected ina bridge of the callingend of the cord circuit by means of a pair ofsprings l9 of a listening key which may be any of the usual or desiredtypes.

A ringing generator 20 having one pole grounded is arranged to deliveralternating current through suitable branches 21 and 22 containingresistance. lamps to the tip and sleeve sides respectively of the cord(ircuit. For example, pressure upon the springs 23 ot' a suitableringing key connects the tip spring of the pair with the generator andimpresses upon the tip conductor oi the telephone line a suitableringing cur rent which is arranged to operate the subscribers bell l atthe station D. At the same time the sleeve spring connects in itsforward position with a conductor 24 containing a 50 ohm noninductiveresistance 25, and leading to the bar 9*. The operation of the otherpair of springs 26 connects on the other hand the ringing generator withthe sleeve conductor of the line and thereby operates the bell locatedat the station C, the tip spring being simultaneously grounded. I

The operation is as follows: The subscriber A desiring a connectiontakes up his receiver with the result that current flows from the mainportion of the battery y B serially over conductor 9, line relay R thesleeve its conductor of the telephone line, through the transmitter andreceiver at the substationan'd thence back to the central oiilce overtip conductor 2, the line relay R, and through ground back to thegrounded pole of the battery. The relays It and R are energized by thiscurrent and close the localcircuit of the signal lamp S which is lightedto indicate the fact of the call at the central ofiice. Upon observingthe signal the operator inserts the plug P in the answering jack of theline L, thereby establishing other paths for current from the battery13. Instead of flowing through the tip high resistance line relay R, ashunt path is now I provided for the current through the tip supervisoryrelay T, which is 'o'i comparatively low resistance and which is nowplaced under the control of the subscriber, since it is responsive tocurrent flowing over the telephone line. Similarly, the current whichbefore followed the path through the high resistance line relay R nowfinds an easier path through the sleeve supervisory relay 1' and thenceover the telephone line. Either the relay R or R, or, in case ofcertainline re sistances, both, will fall back now to render the line signalinoperative. The sleeve relay 9' will therefore be operated to close thelocal circuit of the lamp S Owing to the fact that the subscribersreceiver is off the hook, the tip relay 1" is now energized so that thelamp S remains dark even though the sleeve supervisory relay 1' beoperated. The operator connects her receiver with the cord circuit toconverse with the calling subscriber. Her transmitter is now charged bycurrent'from the battery. B ,.which linds a. path .the branch containingthe said supervisory relay.

4 supervisory relay is therefore operated toclose the local 'circuit olthe supervisory lamp S, which owing to the v fact that thetip-supervisory relay r is' not yet oper-- through the retardation coil15 and through the transmitter 16 to earth. The sound waves impingingthe diaphragm of the transmitter 16 set up variations in the currentflow and effect the charge upon the condenser c which causes a flow ofcurrent through the primary winding of her induction coil correspondingto speech waves. Upon learning that a subscriber upon the line L isdesired the operator tests the condition of the wanted line in the usualmanner by touching the tip of her calling plug to the test ring of oneof the multiple jacks. If the line is busy the said test rings areconnected through the sleeve strand of the inserted plug with the livepole of one of the batteries B or B'-, and will be raised to a potentialof about 24 volts. The tip of the testing plug, however, is only at 18volts so that a flow of current through the said test relayresults,which relay attracts its armature and closes a path for current throughthe primary helix of the operators induction coil 17 This causes a clickin'the operators receiver and indicates to her that the line is busy.

4 If the line is idle, the test rings are at the same potential as thetip of the plug, that is 18 volts all being connected with theintermediate poles of the batteries, and no click is received. Thecalling plug P is therefore inserted and the set of springs 23 or 26operated to ring the desired subscriber. It the subscriber located atstation 0 is wanted, ringing springs 26 are operated-to connect thegenerator 20 with the sleeve conductor. It is apparent that the ringingcurrent has two paths, one being over the sleeve conductor to thesub-station, and the other'being back through theline relay R andthe'larger portion of battery B to ground. The latter path, however, isof high resistance so that a sufiicient current will flow over theformer path to opcrate the subscribers bell. The lamp S does not lightduring ringing, even though the ringing current might tend to operatethe relay R for the reason that the cooperating relay R is shunted bythe tip ringing spring 26. In case the subscriber responds during thesending of the calling current therefore, the line relay R does notrespond for the reason that it is shunted by the tip spring 26.

In case the subscriber D is wanted, the springs 23 ot' the ringing keyare depressed, the tip spring serving to connect the generator with thetipconductor, while the sleeve spring connects a shunt paththrough thenoninductive winding 25 around the line relay R The resistance andimpedance of the line relay R prevents the passage of the ringingcurrent to such an extent as to deprive thesub-station of sufficientcurrent to operate its bell, while the said shunt path prevents theoperation of the line relay R? in case'the subscriber responds duringcalling. 1 g y in case of the release of the ringing key before thecalled subscriber s response, the supervisory relay '1 is included in alocal circuit which consists of the sleeve strand s-, the sleeveconductors of thojaclcs, the portion of the sleeve conductor 3 includingthe-winding of the line relay R the omnihusbar 9 and the smaller portionof the battery B included between the said bar 9* and This ated, islighted and indicates to the operatotth'at the tit) called subscriberhas not yet responded. At the satire time the spring 10 of the relay 1"closes its forward contacts thus completing the tip strand L of thetrunk circuit l' r conversational purposes. Upon the rosptmso ot' thecalled subscriber, the tip supervisory relay r is operated by currentfrom the battery it [lowing o\'oi the line circuit and thuscxtinguishosthe supervisory lamp H The subscribers are now in communication and thebattery B is furnishing current. over the line L for transmissionpurposes and for the operation of supervisory relays r and r The batteryB is simultaneously providing the subscriber upon lino [F with currentlot transmission and for the operation of relays r and 'r.

At the termination of the conversation the subscriber's return theirreceivers to the hooks with the result that,

the line circuits are opened-and the tip supwrvisory relays are deprivedof operating current, thereby closing the circuits of the supervisorylamps S autLS which are lighted to indicate the. fact. ol' the cud'ofthe conversation to the operator. The sleeve supervisory relays are notdoenergizod at this time owing to their incitision in the local circuitswith the smaller portions of the batteries li and B Even though therelays R which are also included in those local circuits he nowenergized, the line signals S do not operate owing to the fact that. therelays it remain donorgized. Upon ohsorving the supervisory signals theoperator takes down the connection and restores all parts to normalcondition.

it will he understood that the several grounds men iionedmay he thecommon otlice ground or the common oflice return and that theproportions of the relays and other parts mentioned herein are notintended to be arbitrary and may be varied according to tho con .litionsof pra tice.

Inst ad of thespecial party lino shown and described,

' other types of line may ho employed and additional parties may heplaced thereon. The generator may be arranged to deliver pulsatingcurrent of different.charat'lcr to tho line, or it. may send current ofdifferent frequent-ir s thorooverand the substations may be suitablyarranucd to r p nd to such currents of different. charactors it will henoted that whenever ihoriuging gem orator is conn cted with one side oltho lino a shunt is suitably arranged around the lino relay associatedWilli tho opposite side oi tho lino. employed lor metallic ringing thoreturn path t'orcurront would be provided through the said shunt paths.

1 claim:

1. in a telephone system, the combination with a telephone lino, of twoline oloct'ro ninguels therefor, one in series with oach limb of lltiline, a line signal controlled by said electionia:xnots. n stun-co ofcurrent. associated with tho line. means at tho subscriber's station forcausing current from said source to traverse said electro-niagnots toactuate said signal. and means for shuntin; one of said mag-nets toretire said si znal or prevent Its opo' ion when a connection isestablished with the title, substantially as described.

2. in a telephone s stem. the combination with a telo' phone line, twohigh resistance ole ll'U-lllHLt'lllLS oins rially connected in each limbof the line at the central otlit'o, a

in case tho generator is lino signal controlled by said magnets, tuoanscontrolled established with the line for convei described.

ation, substantially as phone line, or two line (Electra-magnetstherot'or, one connected in each line conductor at the central oilice, aline signal controlled by said etectro-magncts, a source of currentassociated with the line, means at the subscriber's station for causingcurrent. from id source. to operate said electro-ma suets to operate the.ignal, means for rendering one of said eloctro magnets inoperative whena connection is established with the line for conversation to therebyrender the line signal inoperative, and means for sending current overone of said electroman'nets whereby said signal is not operatedsubstantially as described.

t. in a telephone system, the combination with a lPll. phone line, oftwo high resistance rel ys therefor at. the central otiico, oneconnected with or lino conductor, a. line signal having, its circuitvclosed through normally open contacts of both said relays, a source ofcurrent; associated with the line at the central otiice, means at thesubstation for closing the circuit. or said source over the metallicline to energize said relays and thereby to operate said signal, andmeans to deprive one of said relays ot' operating cur rent when aconnection is established with the line for convex atiou to therebyrender the line signal inoperative while sending-current over the otherof said relays, substantially as described.

5. in a telephone system, the combination with a tele phone line, of twoline relays therefor at the central.

' pair of supervisory relays a. soclated therewith, and means forcontracting said relays in shunt of said line relays when a connectionis established with the line, substantially as described.

Ti in a telephone system, the combination with a telephone line, of twoline rel: 5 associated therewith, a cord circuit. a pair 01' supervisoryrelays associated with said cord circuit, and means for including one ofsaid super visor-y relays in parallel with one of said line relays whenconnection is established with the line by said cord rcuii. the othersupervisory relay being arranged to be actuated by current flowing overtire line circuit, substantially as described 8. In a telephone system,the combination with a tele' phone line, of a separate electro-magnetassociated with each line conductor, a line signal controlled by saidelectro magnets. and means for sending ringing current orer the path ofone at said in: "nets without actuating said signal. substantially asdescribed. I

.l. in a telephone system, the combination with a telephono line, or anelectro-iuagnet associated with each line conductor, a signal for theline operated whenever both of said electroniagnets are energized, andmeans for sending ringing; current out over the path of either of saidmagnets without operating said signal, substantially as described to. Ina telephone system, the combination with a tele phone line, of an(l0l'llU-ll\:l;:ll(.i; assuciatcd with each line conductor, a linesignal controlled by both said electronntunots, the calling generator.and means for connecting; said generator with one litre conductor andsending ringing current through one of said magnets and at Lln same timerendorii said olecirtstuagnct in the other line conductor inopcr. ivo,whereby the said line signal, is not actuated. substantially asdescribed.

ii. in a tclophoi-ie sy tom, the combination with a micphone line. ot anolectro-maunct associated with each line t'uiltillclut, a line si, allcontrolled by said electromagnets. a callii: gonorator. lll s forconnecting said generator with the line to call a wanted subscriber, andat the same time shuntin: ono of said eloctro-ntagnets to prevent theoperation ot said signal, substantially as dosoril-t'tl.

IL, in a telephone system, the rinbinatiou with a tote phone line, of aline relay assu ited with each line coil Cit -w.ith the other side ofthe line,

vented from operation during ringing, substantially as described.

13. in a telephone system, the combination with a tele phone line. of aline relay associated with each line conduetor, a line signal having itscircuit controlled through contacts 01' both said relays, a ringinggenerator-means fut-connecting said generator with either side of and atthe same time rendering the line relay connected with the other side ofthe line inoperative, whereby id signal is prevented from operationduring ringing si'ibfzi'n tialiy as described.

' 14. in a. telephone system, the com hi'nition with a telephone iinzfota pair of relays, one in series with each limb the line r of said line,a central source of current permanently com i nected to said linethrough the coils of said relays, 21 line I signal controlled by saidrelays; a cord circuit zitlapted to be conneL-ted with,suid line forriversti a 'liji'ervisury relay iisocinted with the cord circuit. 111for connecting said supervisory relay in series with one of said linerelay and a portion oi nriid central source of current. when :1connection in eii'tiibiished with a telephone line, and meansthereaftfi'ren current flows in the telephone line, Y S'z'lid 'i'i n erelay of its :ictnntin: (-nrrrnt uitlr its ('irrnit, substantially as(inscribed. d v inc :lt (fliirngof county of (Junk, Siute 0i Ilii %Olfi.this I'M h day of December 1590;.

Witnesses In mnm Liawm A .n as,

